Anyone with a speaking part is going to have to speak with a British accent, other countries have their own wizard schools so the students at Hogwarts would be British, and they are not going to...
well in the last book(deathly hollows) he dies but is brought back by the stone of ressurection that dumbledore left him and he didnt die again because when he disarmed malfoys wand he became the...
i doubt it. i dont think the director would do that to people but i think that there is not really any time to audition anymore considering that we r up to the 6th movie. then its just part 1 and 2...